Vasorelaxant Effects of Wild Jujube Leaf Aqueous Extract: Endothelial NO/cGMP/SERCA Signaling, Antioxidant Activity, and AI-Based Molecular Docking

Ziziphus lotus (L.) Lam (wild jujube) leaves are traditionally used in Moroccan medicine to treat hypertension. The present study evaluated the aqueous extract of Z. lotus leaves (ZLAqExt) for its vasorelaxant effects, mechanisms of action, acute toxicity, antioxidant potential, and phytochemical profile. In phenylephrine-precontracted rat aortic rings, the ZLAqExt induced concentration-dependent relaxation (Emax = 79.25 ± 2.77% at 10−1 mg/mL). The mechanism of action was investigated using specific antagonists and blockers. Complete inhibition by endothelium denudation, and preincubation with L-NAME, hydroxocobalamin, ODQ, and thapsigargin confirmed endothelium-dependent nitric oxide (NO)/cyclic GMP (cGMP)/sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) pathway involvement. A partial inhibition by BaCl2, indomethacin, calmidazolium, and KCl indicated cyclooxygenase (COX), endothelium-derived hyperpolarizing factor (EDHF), and inward-rectifier potassium (Kir) channel contributions. Acute oral toxicity did not show any mortality at 2 g/kg BW in mice. The extract displayed potent antioxidant activity (DPPH IC50: 18.12 ± 1.49 µg/mL; β-carotene bleaching IC50: 8.3 ± 0.014 µg/mL). UHPLC-ESI-MS identified rutin as the major compound, followed by 3′,5′-di-C-β-glucopyranosyl phloretin with high docking affinity for guanylate cyclase and SERCA pump. The presence of flavonoids in the ZLAqExt might have mediated its vasorelaxant effects, supporting its traditional use as an antihypertensive. Our results highlight that Z. lotus is a potential natural therapeutic agent against vascular dysfunction-related cardiovascular disorders.